Due to increasingly higher demands for safety of ground fault circuit interrupters (GFCIs), it is desirable to provide safety measures for the GFCIs to allow an end user to find out whether the components of the GFCIs are working properly, whether the GFCIs are properly wired, and whether there is power to the output load. Additionally, it is desirable to extend the life span of the GFCIs by designing a feature that can protect the GFCIs from high voltage surge, such as lightning. The invention described below is designed to encompass the safety functions set forth above.